Whisk together cornmeal, flour, baking soda, baking powder, salt and sugar in a large bowl. Whisk together eggs, buttermilk, yogurt and oil. Pour buttermilk mixture into cornmeal mixture and stir until just combined. Fill each muffin cup 2/3 full with batter.
Bake for 15-18 minutes, until tester just comes out clean. Do not overbake!